import math
l = input().split()
x1 = float(l[0])
y1 = float(l[1])
x2 = float(l[2])
y2 = float(l[3])

a = pow((x2 - x1), 2) + pow((y2 - y1), 2)
ans = math.sqrt(a)
print(ans) import math math l = input().split() l input().split() ().split () input split x1 = float(l[0]) x1 float(l[0]) float l[0] l 0 y1 = float(l[1]) y1 float(l[1]) float l[1] l 1 x2 = float(l[2]) x2 float(l[2]) float l[2] l 2 y2 = float(l[3]) y2 float(l[3]) float l[3] l 3 a = pow((x2 - x1), 2) + pow((y2 - y1), 2) a pow((x2 - x1), 2) + pow((y2 - y1), 2) pow((x2 - x1), 2) pow x2 - x1 x2 x1 2 pow((y2 - y1), 2) pow y2 - y1 y2 y1 2 ans = math.sqrt(a) ans math.sqrt(a) math.sqrt math sqrt a print(ans) print ans l = input().split() input().split() l x1 = float(l[0]) float(l[0]) x1 y2 = float(l[3]) float(l[3]) y2 y1 = float(l[1]) float(l[1]) y1 a = pow((x2 - x1), 2) + pow((y2 - y1), 2) pow((x2 - x1), 2) + pow((y2 - y1), 2) a ans = math.sqrt(a) math.sqrt(a) ans x2 = float(l[2]) float(l[2]) x2
import math
l = input().split()
x1 = float(l[0])
y1 = float(l[1])
x2 = float(l[2])
y2 = float(l[3])

a = pow((x2 - x1), 2) + pow((y2 - y1), 2)
ans = math.sqrt(a)
print(ans)